1. Field of the Invention
The invention relates to components for an improved system for pick-up impression making at a dental implantation site, comprising an abutment, an abutment replica and an impression coping. The invention also relates to a series of abutments and to a set comprising an abutment and an impression coping.
2. Description of Related Art
Dental implant systems are widely used for replacing damaged or lost natural teeth. In such systems, an implant is placed in the jaw of a patient in order to replace the natural tooth root. An abutment structure comprising one or several parts may then be attached to the implant in order to build up a core for the part of the prosthetic tooth protruding from the bone tissue, through the soft gingival tissue and into the mouth of the patient. On said abutment, the prosthesis or crown may finally be seated.
The final prosthesis must be sized and configured so as to naturally fit with the remaining teeth of the patient, both for functionality and aesthetics. To this end, a dental technician needs to try out a proper prosthesis for the individual patient, using a model of the jaw of the patient, said model including the implant and possibly an abutment structure. To provide such a model, so called master cast modelling techniques are used.
One category of such modelling techniques is the so-called xe2x80x9cpick-upxe2x80x9d method. A pick-up method could be described by the following subsequent steps:
An impression cap is placed on the implant and/or the abutment.
An impression material is applied to the jaw, such that said impression cap is embedded in the impression material.
The impression material is removed from the jaw, bringing along the impression cap still being embedded in the impression material. The impression material now has the inverse form of the jaw with the impression cap at the site of the implant/abutment.
A replica replicating the shape of the implant and/or abutment is inserted into the embedded impression cap, in the same manner as the original implant and/or abutment was connected to the impression cap.
A moulding material is poured into the inverse form of the jaw made out of the impression material and around the replica and let to harden.
The impression material is removed from the hardened moulding material, said moulding material now forming a true, or non-inverse model of the jaw with the replica replacing the original implant/abutment.
In the following, reference will be made to some prior art documents describing pick-up methods or components to be used therewith.
U.S. Pat. No. 6,068,478 (Grande et al.) discloses an impression system including an impression cap for transferring an end, protruding from a human tissue structure, of an implant which is fitted in the human body, including possible superstructures, to a master cast. The outwardly directed implant end has an undercut contour on its outside, and the impression cap has a geometry which complements the undercut contour and engages therein. The undercut contour is formed either by an implant geometry tapering in a trumpet shape towards the implant bed, or by a recess near the implant end.
In said U.S. Pat. No. 6,068,478 (Grande et al.), a superstructure part is described to be screwed into the implant such that an abutment of the superstructure is projecting above the implant shoulder. For taking an impression of the mouth situation to a finished master cast, a slide sleeve is first of all pushed onto the conical superstructure. Then, an impression cap is pushed over the slide sleeve. At the very bottom, the impression cap has a cap shoulder, which is complementary to the implant shoulder. On the outside, the cap shoulder is surrounded by an elastic snap element directed inwards, so that it can snap over the implant shoulder and releasably grip an undercut contour on the implant head. An impression tray filled with impression compound is now pressed onto the implantation site. After withdrawing the impression tray, the impression cap and the slide sleeve remain embedded in the impression compound, and the impression is obtained. An analogous manipulation implant having a shape corresponding to the conical superstructure is now pushed into the slide sleeve. Finally, a manipulation shoulder sleeve, having a manipulation shoulder corresponding to the implant shoulder is pushed over the manipulation implant until the manipulation shoulder is held by the snap element of the impression cap. Modelling compound is lastly poured onto the impression and the master cast is obtained.
In said U.S. Pat. No. 6,068,478 (Grande et al.), another impression method is used if another type of superstructure, for example an angled superstructure is attached to an implant. In this case, an impression cylinder is screwed onto the superstructure and a laterally open impression cap is pushed onto the superstructure such that is grabs the implant shoulder. The impression is taken using the impression tray filled with impression compound, which impression is obtained after withdrawing the impression tray, and in which the impression cap and a hollow space according to the impression cylinder and the conical superstructure remain behind. In the next step, the impression cylinder is pushed into its hollow space and the manipulation shoulder sleeve is attached, and modelling compound is then filled through the manipulation shoulder sleeve so that the whole hollow space is filled up. Modelling compound is now poured onto the impression and, after removing the impression tray in which the impression cylinder remains, the finished mater cast is obtained.
It is further mentioned that the slide sleeve might be omitted if the hollow space remaining in the impression cap, and left by the selected abutment inside the impression cap, is filled with impression compound. Also, the slide sleeve and the impression cap may be combined and designed as one piece.
U.S. Pat. No. 6,159,010 (Rogers et al.) discloses a dental coping for placement over an abutment post that is attached to and protruding above a dental implant. The coping includes a base portion having an internally tapered surface for mating with a support surface of the implant. A wall extends away from the base portion for enveloping the abutment post. The wall includes at least one aperture for allowing wax material to pass therethrough when taking an impression of the implantation site.
U.S. Pat. No. 5,688,123 (Meiers et al.) discloses a transfer cap for dental implants that are to be used when taking an impression for forming a master cast model. This transfer cap is adapted in form and size to the built-up part or abutment of the implant and carries one or more resilient flaps extending over the shoulders of a conical area of the built-up part.
WO 99/29255 (Morgan) discloses an abutment analogue having a head portion being formed with retention means such as an annular groove.
EP 0 190 670 (Lustig) discloses a prefabricated abutment that may be used in combination with a prefabricated sleeve-like coping which is telescopically mated to the post.
An object of this invention is to provide components for a system for improved function when using pick-up impression methods, and a method using said components.
In a first aspect of the invention, the above object is achieved by an abutment for connection of a dental component to an implant, said abutment comprising an implant contacting region and a component support region, said component support region having a maximum diameter and extending coronally of said maximum diameter to a coronal end. Said component support region is provided with a component engagement means being arranged for releasable engagement with said component by linear displacement of said dental component in relation to said abutment. Said component engagement means is located at a position closer to said maximum diameter than to the coronal end of the component support region.
The term xe2x80x9ccoronalxe2x80x9d is here and throughout this application used to indicate a direction towards a head end or trailing end of the component discussed. For example, in a situation where an abutment is connected to an implant, the coronal direction would be a direction towards the part of the abutment being directed away from the implant. Likewise, the term xe2x80x9capicalxe2x80x9d indicates a direction towards an insertion end of the component. For an abutment connected to an implant, the apical direction would be a direction towards the implant. Thus, apical and coronal are opposite directions.
However, if parts of a component or a system are angulated in relation to each other, the apical and coronal directions of the different parts, respectively, may not be coinciding. For example, this would be the case for an abutment where the component support region of an abutment is angled in relation to the implant contacting region, a so called angled abutment. Herein, when discussing the apical direction of the component support region, a direction towards the maximum diameter of the component support region is referred to. The coronal direction of a component support region is a direction away from said maximum diameter, towards a free end of the component support region.
The component engagement means is arranged for releasable engagement with said component, said engagement being accomplished by linear displacement of said dental component in relation to said abutment. In particular, the engagement should be releasable by linear displacement only of the component in relation to the component support region. This is advantageous since the component engagement means might among other functions be used for locking an impression coping for pick-up impression making to the abutment. In pick-up impression making, any rotational movements between the impression coping and the abutment when releasing the coping from the abutment should preferably be avoided.
The retaining force of the engagement between the abutment and the component may be selected for different applications. For connection of an impression coping for pick-up impression making to the abutment, the retaining force should be large enough to securely retain the impression coping on the abutment in a well defined position, but not so large that the impression coping may easily be removed from the abutment together with impression material into which it is embedded.
Further, the component engagement means should preferably provide a stable locking of the component to the abutment at a well defined location on the abutment. For the above mentioned use with impression copings, it is advantageous that a prosthesis manufactured after master-cast making may be attached to the abutment in the same position as the impression coping was during the previous impression making by which said master cast was made.
The component engagement means is provided at a component support region of the abutment, which is extending coronally of a maximum diameter of the component support region of the abutment. This arrangement provides advantages over prior art where a portion providing a maximum diameter of an abutment or implant is used as a locking means for retaining impression components. Thus, in this prior art, components to be attached to the locking means will need to have a maximum outer diameter larger than the maximum diameter of the abutment or implant in order to be seated thereto. Since in these prior art systems the maximum diameter is provided at a position down in the soft gingival tissue overlying the bone tissue where the dental implant is situated, this means that the gingival tissue will have to be pushed aside and risk being damaged when attaching a component to the abutment. Also, the large diameter of the component may make it difficult to attach or remove the component from the abutment without said component colliding with possible teeth adjacent to the implant. Where the adjacent teeth are very close set, the diameter of the component might even be too large for the component to pass between the teeth to be set on the abutment. However, the arrangement disclosed above diminishes these problems in providing a possibility of attaching components having a relatively small outer diameter to the abutment.
Further, the component engagement means of the present abutment is provided closer to a maximum diameter of the component support region than to a coronal end of said region. This provides an advantage in that a relatively large portion of the component support region will extend coronally of the component engagement means. Consequently, said portion of the component support region may be modified by the dental technician, without compromising the function of the component engagement means. Such modifications are sometimes made for customising standard abutments so as to adapt to the needs of an individual patient. Thus, the specified position of the component engagement means allows components to be attached to the abutment independent of whether the latter has been modified or is left in an original standard appearance.
The component engagement means being provided closer to said maximum diameter than to the coronal end of the abutment means that it is provided at a distance from said maximum diameter being less than 50% of the distance between said maximum diameter and said coronal end of the abutment. Advantageously, it may be provided at a position from said maximum diameter being less than 35% of the distance between said maximum diameter and said coronal end of the abutment, and most preferred less than 25%.
According to a second version of the first aspect of the invention there is provided an abutment for connection of a dental component to an implant, comprising an implant contacting region and a component support region, said component support region having a maximum diameter and comprising a shoulder portion presenting an outer surface, and a post portion extending coronally from said shoulder portion to a coronal end of the abutment and presenting an outer surface forming an angle less than 180xc2x0 with said outer surface of said shoulder portion. Said component engagement means is arranged for releasable connection of said component to said abutment by linear displacement of said component in relation to said abutment. Said component engagement means is provided at the post portion, at a position being closer to the shoulder portion than to said coronal end of the abutment.
It lies in the term xe2x80x9cshoulder portionxe2x80x9d of the component support region that it should be structured and adapted to support a component at least partly from xe2x80x9cbelowxe2x80x9d, that is from the apical direction. In other words, the projection of a normal to the outer surface of the shoulder portion onto the longitudinal axis of the component support region would extend in the coronal direction.
In contrast, the post portion of the component support region may have an outer surface being parallel to a longitudinal axis of the abutment, that is, a normal of said outer surface is directed transversely to said longitudinal axis. However, there are other alternatives, and perhaps more advantageous, where the outer surface of the post portion is forming an angle with the longitudinal axis.
The definitions and advantages over prior art described in relation to the first variant of the abutment are equally applicable for this second variant of the abutment.
In addition, in this second variant, the shoulder portion residing apically of the component engagement means will provide a stable base for support of said component, independently on whether the post portion of the abutment is modified or not. This is particularly advantageous if the post part is modified in a way that compromises its function for supporting a component. For example, if a component is adapted to the abutment, having an inner surface closely following the post portion and the shoulder portion, it will be in contact with both the post portion and the shoulder portion if set on an abutment having its original shape. However, if the post portion is customised, the component seated on the abutment will not follow the new customised outer contour of the post portion. Anyway, such a component may be securely seated on the abutment, since the shoulder portion rests unmodified and may provide the necessary support.
A stable and repeatable location of components on the abutment is particularly important when using pick-up impression techniques, in order to provide an accurate master cast model and correctly located prosthesis.
The component engagement means is provided closer to said shoulder portion than to the coronal end of the abutment means such that the component engagement means is provided at a distance from said shoulder portion less than 50% of the distance between said maximum diameter and said coronal end of the abutment. Advantageously, it may be provided at a position from said shoulder portion being less than 30% the distance between said maximum diameter and said apical end of the abutment, and most preferred less than 20%.
Preferably, the angle between the outer surface of said shoulder portion and the outer surface of said post portion is in the range 100 to 160xc2x0, more preferred 120 to 150xc2x0, most preferred 130 to 140xc2x0.
Advantageously, said component engagement means may be provided at a transition between said post portion and said shoulder portion. This location maximises the part of the post portion extending coronally of the component engagement means, and thus the part of the abutment being available for modification by a dental technician.
Returning now to the shapes of said post portion and shoulder portion, the outer surface of the post portion may advantageously be tapering inwardly in a coronal direction of the abutment. The taper has the advantage that it allows more lateral play in an initial stage of attaching a component to the post portion, as is common for example with impression caps. With a post portion having an outer surface being parallel to said longitudinal axis, any component to be threaded on the post portion must be brought into axial alignment with the post portion. However, if the post portion is having a conical outer surface a certain misalignment when starting the attachment is possible. Also, the taper may contribute to providing an engagement function with said component.
In particular, an outer surface of the post portion forming an angle preferably less than 20xc2x0, more preferred less than 15xc2x0, most preferred 6xc2x0 with a longitudinal axis of the abutment has been found to be useful.
Also the shoulder portion might advantageously taper inwardly in a coronal direction of the abutment. In particular, the conical outer surface of the shoulder portion may form an angle in the range 40 to 60xc2x0, preferably 50xc2x0 with a longitudinal axis of the abutment.
One embodiment of an abutment according to any of the two variants of the first aspect of the invention described above is further having an extension region being provided between said implant contacting region and said component support region. Such an extension region is useful to extend the height of the abutment so as to pass through the gingival soft tissue overlying the bone tissue where the implant is placed.
The outer surface of said extension region may be parallel to a longitudinal axis of the abutment, or it may be tapering outwardly in a coronal direction.
In an abutment according to this embodiment, also including a post portion and a shoulder portion, the extension region may favourably be arranged such that the transition between said extension region and said shoulder portion defines the maximum diameter of the abutment.
With the abutments according to said first aspect of the invention, said component engagement means might advantageously comprise at least one protrusion or indentation in an outer surface of said component support region. Such a protrusion or indentation might for example be a rib or groove extending at least partly around a circumference of the outer surface of said component support region. These shapes are particularly useful to provide an engagement means onto which components may be snap-locked.
In a second aspect of the invention, there is provided a series of abutments according to said first aspect of the invention, each abutment having a maximum diameter of said component support region, and said maximum diameter being constant for all abutments in said series.
Alternatively, there is provided a series of abutments according to said second variant of the first aspect of the invention, wherein said angle formed between said outer surface of the post portion and said outer surface of the shoulder portion is constant for all abutments in said series. This feature makes it possible to use components having the same shape although not necessarily the same size for different abutments in said series.
Also, there is provided a series of abutments according to said second variant, wherein each abutment is having a longitudinal axis and further comprising an implant contacting region and an extension region extending between said implant contacting region and said component support region, wherein
said extension region presents an outer surface forming an angle ("PHgr") with said longitudinal axis,
said shoulder portion presents an outer surface tapering inwardly in a coronal direction, said outer surface forming an angle ("khgr") with said longitudinal axis,
said post portion extending coronally from said shoulder portion and presenting an outer surface tapering inwardly in a coronal direction forming an angle (xcfx86) with said longitudinal axis being less than the angle ("khgr") formed by the outer surface of the shoulder portion with said longitudinal axis, wherein,
said angle ("khgr") between the outer surface of the shoulder portion and the longitudinal axis and said angle (xcfx86) between the outer surface of the post portion and said longitudinal axis are constant for all abutments in said series,
whereas the angle ("PHgr") between the outer surface of the said extension region and said longitudinal axis varies between different abutments in said series.
According to this embodiment, the angles of the component support region are fixed, leading to the advantage of a conformity in the shape of components adapted for different abutments.
In a third aspect of the invention, there is provided an abutment replica, comprising a component support region having the outer shape of the component support region of an abutment according to said first aspect of the invention, including the component engagement means.
In an embodiment of said replica it further comprises a bore extending from an apical end of said replica, at least to a position coronally of said component engagement means. In this embodiment, at least part of the component support region may be cut off, leaving a replica comprising a remaining apical region and the component engagement means of the support region and being provided with a through bore. This possibility is used when making a master cast of a modified abutment, which will be described in more detail in the specified part of the description. The replica according to this embodiment is advantageous since it may be used both for situations where the abutment is left in its standard appearance (in its original state) and for situations where the abutment is modified (in a cut-off state).
According to a fourth aspect of said invention, there is provided an impression coping for pick-up impression making of a dental abutment attached to a dental implant, comprising an abutment surrounding region for surrounding said abutment, said abutment surrounding region having an apical end and a coronal end, and having an inner wall being provided with abutment engagement means being arranged for releasable engagement with said abutment by linear displacement of said impression coping in relation to said abutment, said component engagement means being located closer to said apical end than to said coronal end.
In prior art systems, locking means such as flaps are sometimes provided at the end of an impression cap for engagement over and around an abutment. In these constructions, the locking means will contribute to an enlarged outer diameter at the apical end of the impression cap, leading to unnecessary compression of the soft gingival tissue surrounding the abutment. Further, the placement of the locking means at the end of the impression caps often leads to a low attachment level of the cap down in the gingival tissue of the patient.
In other prior systems there are locking means provided close to the coronal end of the impression cap. These systems have the disadvantage that the abutment on which the impression cap is to be seated may not be modified below said coronal end, if the impression cap shall still be attachable to the abutment.
The above mentioned disadvantages may be avoided by the location of said abutment engagement means on the inner wall of the impression coping, closer to said apical end than to said coronal end according to this third aspect of the invention.
In a first variant of said impression coping, the abutment surrounding region of the impression coping comprises a shoulder contacting portion having an inner wall and a post surrounding portion extending coronally from said shoulder contacting portion and presenting an inner wall forming an angle larger than 180xc2x0 with said inner wall of said shoulder contacting portion, wherein said abutment engagement means are provided at the post surrounding portion, at a position being closer to the shoulder contacting portion than to the coronal end of the abutment surrounding region.
The shoulder contacting portion is intended to contact a shoulder portion of a corresponding abutment. Accordingly, the projection of a normal to the outer surface of said shoulder contacting portion onto a longitudinal axis of the component surrounding region would extend in the apical direction.
The post surrounding portion may have an inner wall having various shapes. It may be formed such that the entire inner wall contacts a post portion of an abutment. However, it may also be formed so as to contact the post portion of an abutment only with a part of said inner wall. Some such embodiments will be described below.
In first variant of the impression coping, the location of the abutment engagement means on the inner wall of a post surrounding portion extending from a shoulder contacting portion results in a position of the locking means where the diameter of the abutment on which the impression coping is to be seated is relatively small, as compared to the diameter at a shoulder portion of the abutment. Thus, this location of the locking means allow more construction variations of the locking means to be used without having to increase the outer diameter of the impression coping at the locking means beyond the maximum diameter of said abutment.
Further, the shoulder contacting portion is useful for increasing contact and stability in the interaction with said abutment. This is particularly important as the impression coping will be used in pick-up impression methods, where it will first be attached to an abutment being fixed to an implant, thereafter embedded in impression material and removed from the abutment together with said impression material, and finally an abutment replica will be inserted into said impression coping. For succeeding with this method, both the abutment and the abutment replica should be securable in the impression coping with great accuracy, to which said shoulder contacting portion contributes.
Preferably, said abutment engagement means is provided at a distance from said shoulder contacting portion being less than 50% the distance between said shoulder portion and said coronal end, preferably less than 30%, most preferred less than 20%.
The abutment engagement means may be provided at a transition between said post surrounding portion and said shoulder contacting portion. Further, the abutment engagement means may comprise at least one protrusion or indentation, such as a rib or groove, in an inner wall of said abutment surrounding region.
Preferably, the impression coping is having a through passage extending from a coronal end to an apical end of the impression coping. This is advantageous since impression material may then be introduced through the coronal end into the impression coping, thus increasing the fixation of the impression coping in the impression material. Also, in this embodiment the impression material introduced into the impression coping will contact part of the abutment, and thus provide an open space replicating said abutment part. This open space may be used for guiding the later introduction of an abutment replica, or as will be described in the detailed part of the description, as a form for forming a model of a customised abutment.
According to a second variant of the impression coping there is provided an impression coping being having a through passage, a longitudinal axis and an abutment surrounding region, wherein the inner walls of said abutment surrounding region comprises at least one abutment contact surface for contact with said abutment, and at least one space forming surface to be spaced apart from said abutment in order to provide a space between said space forming surface and said abutment, and in a transversal section of said post contacting region, a distance from said longitudinal axis to said post contact surface is shorter than a distance from said longitudinal axis to said space forming surface.
According to this second variant of an impression coping, impression material may be introduced in said space between said space forming surfaces and said abutment. However, there are also abutment contact surfaces, that contacts the abutment thus providing a stable contact surface. This embodiment is particularly useful in that it may advantageously be used both for taking impressions of both standard and modified abutments, as will be described below.
When taking an impression of a standard abutment, the abutment contact surfaces will contact the standard abutment. Impression material may optionally be introduced into the spaces formed by the space forming surfaces, but this is not necessary. The abutment contact surfaces will namely normally provide enough surface to guide the later insertion of an abutment replica into exactly the same position as the abutment had inside the impression coping.
However, when taking an impression of a modified abutment, all of the abutment contact surfaces will probably not be in contact with the modified abutment. At least a portion of the abutment contact surfaces will most likely not contact the customised abutment, due to the modified shape thereof. In this case a composite space is formed between the abutment and the inner wall of the impression coping, said composite space being composed by a space created between the abutment contact surface and the modified abutment and said space between said space forming surface and said abutment. Impression material may be introduced into the impression coping and into the composite space formed between said impression coping and the modified abutment. Thus, when removed from the abutment, the impression material together with the impression coping will form an empty space having an inner xe2x80x9cmodifiedxe2x80x9d shape corresponding to the shape of the modified abutment, said inner shape being subsequently used for moulding a model of said modified abutment.
Preferably, said space forming surface may be provided with a vent for passage air from said composite space. Thus, when impression material is introduced into said composite space, air may flow through the space formed between said space forming surface and said abutment out through the vent, whereby air bubbles are avoided and proper introduction of impression material is ensured. The space forming surface thus provides an air duct for air evacuation from said composite space.
The vent may be provided by an opening in the space forming surface or possibly by a perforation or other suitable vent means.
Naturally, the abutment may alternatively be modified such that all of the abutment contact surface is still in contact with the modified abutment, and the composite space is related only to the space forming surfaces. The extent to which said composite space needs filling with impression material is dependent on the modification made of the abutment. However, complete filling may normally be ensured by having impression material filled into the entire composite space and flowing out of said vent.
Advantageously, at least one abutment contact surface may be tapering inwardly in a coronal direction. This is particularly useful when the impression coping is to be seated on an abutment having a tapered outer shape.
Said first and second variants of an impression coping may advantageously be combined. The combination of a shoulder contacting portion and post contacting surfaces provides a possibility of ensuring that the impression coping is correctly placed on the abutment. In some prior art systems there are provided impression caps having only a shoulder contacting portion and a post surrounding portion with no abutment contact surfaces. Such prior impression caps risk however being incorrectly placed on the abutment.
At least one abutment contact surface may be provided with a rotational locking means, for rotational locking of said impression coping on said dental abutment. This feature is useful for ensuring a proper transfer of the rotational direction of the abutment fixed to the implant to a master cast model via impression making.
For enhanced attachment into the impression material, the impression coping may be provided with a prolongation region coronally of the abutment surrounding region. Such a prolongation region will also make the impression coping easier to handle. Said prolongation region may further be provided with retention elements for retention of the impression coping in an impression material.
Finally, in a fifth aspect of the invention, there is provided a set comprising an abutment and an impression coping.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.